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EMG Instrumentation

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EMG Instrumentation

  1. 1. SEMINAR TOPIC : Electromyogram (EMG) Rzfafhafx Submitted by :ANKUNShHfn hJhAnhISWAL University Roll no. =110070106006 AEI-4th year
  2. 2. EMG • The bioelectric potentials associated with muscle activity constitute the electromyogram , abbreviated EMG. • Recording muscle activity at rest and during activity (volitional activity) • Requires a lot of cooperation and cannot be performed accurately in patients with severe weakness
  3. 3. Types of EMG MEASUREMENTS • Electrode Categories – Inserted • Fine-wire (Intra-muscular) • Needle – Skin Surface electrodes
  4. 4. Fine-wire Electrodes • Advantages – Extremely sensitive – Record single muscle activity – Access to deep musculature – Little cross-talk concern • Disadvantages – Extremely sensitive – Requires medical personnel, certification – Repositioning nearly impossible – Detection area may not be representative of entire muscle
  5. 5. Surface Electrodes • Advantages – Quick, easy to apply – No medical supervision, required certification – Minimal discomfort • Disadvantages – Generally used only for superficial muscles – Cross-talk concerns – No standard electrode placement – May affect movement patterns of subject – Limitations with recording dynamic muscle activity
  6. 6. EMG Manufacturers • Noraxon • Motion Lab Systems • Delsys
  7. 7. General Concerns • Signal-to-noise ratio – Ratio of energy of EMG signal divided by energy of noise signal • Distortion of the signal – EMG signal should be altered as minimally as possible for accurate representation
  8. 8. Characteristics of EMG Signal • Amplitude range: 0–10 mV (+5 to -5) prior to amplification • Useable energy: Range of 0 - 500 Hz • Dominant energy: 50 – 150 Hz
  9. 9. Factors Affecting the EMG Signal Causative Factors – direct affect on signal • Extrinsic – electrode structure and placement • Intrinsic – physiological, anatomical, biochemical – Intermediate Factors – physical & physiological phenomena influenced by one or more causative factors – Deterministic Factors – influenced by intermediate factors
  10. 10. Maximizing Quality of EMG Signal • Signal-to-noise ratio – Highest amount of information from EMG signal as possible – Minimum amount of noise contamination • As minimal distortion of EMG signal as possible – No unnecessary filtering – No distortion of signal peaks
  11. 11. References • De Luca CJ: The use of surface electromyography in biomechanics. J App Biomech 13: 135-163, 1997 • MyoResearch: software for the EMG professional. Scottsdale, Arizona, Noraxon USA, 1996-1999 • De Luca CJ: Surface electromyography: detection and recording. DelSys, Inc., 2002

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